Method and system for analyzing a movement of a person

Abstract

A system and method for analyzing movement of a person includes: measuring kinetic data as the person ambulates with a pair of removable force sensors affixed to a person's ankles, feet, shoes or lower-limb prosthesis with each of the pair of force sensors on a different one of the person's ankle, feet, shoes or lower-limb prosthesis; obtaining kinematic data as the person ambulates with at least one video camera that video records the person ambulating without markers; and temporally synchronizing the kinetic data and the kinematic data together.

What is claimed is: 
     
       1. A method for analyzing movement of a person, the method comprising:
 a) measuring 3D kinetic data as the person ambulates with a pair of force sensors affixed to a person's ankles, feet, shoes or lower limb prostheses with each of the pair of force sensors on a different one of the person's ankle, feet, shoes or lower limb prostheses, sensing at least pressure force or vertical force, anterior/posterior shear force, and medio/lateral shear force with at least three-axis sensors, storing the 3D kinetic data to a digital memory device, producing a left or right side identified vector quantity with a mobile processor, and wirelessly transmitting the 3D kinetic data at 60 Hz or greater with a transceiver to a computer with a processor and a transceiver; 
 b) obtaining 3D kinematic data as the person ambulates with at least one video camera that video records the person ambulating without markers on the person and in an environment without force-sensing plates; 
 c) temporally synchronizing the kinetic data from the pair of force sensors and the kinematic data from the at least one video camera together using the processor of the computer by: 
 creating a visual event in the 3D kinematic data captured by the at least one video camera and a force event in the 3D kinetic data sensed by at least one of the pair of force sensors; or 
 sending a time signal from the computer to the pair of force sensors and the pair of force sensors transmitting a time-stamped vector quantity to the computer; and 
 d) simultaneously outputting the 3D kinetic data and the 3D kinematic data, and saving the 3D kinetic data and the 3D kinematic data together as a data file. 
 
     
     
       2. The method in accordance with  claim 1 , further comprising:
 orienting a foot segment coordinate system of either of the pair of force sensors with a foot segment coordinate system of the lab space of the video camera by aligning a foot space force vector reported by one of the pair of sensors with a lab space vertical axis created by the video camera. 
 
     
     
       3. The method in accordance with  claim 1 , wherein the patient is an amputee; and further comprising:
 adjusting segment mass properties based on both visual blob segment distribution and choice of prosthesis by realigning mass distribution between a standard mass distribution of a non-amputee and mass distribution of the amputee with the prosthesis. 
 
     
     
       4. The method in accordance with  claim 1 , further comprising:
 rendering the video recording of the person ambulating into a three-dimensional stick figure with a plurality of segments representative of a skeletal model of the person. 
 
     
     
       5. The method in accordance with  claim 4 , further comprising:
 performing Intersegmental Dynamics Analysis (IDA) on a computer model based on the kinematic, the kinetic and segment data by applying joint moments to determine subsequent acceleration of the computer model; and 
 performing Acceleration Analysis (AA) to compute a contribution of net joint moments to forward propulsion of the person. 
 
     
     
       6. The method in accordance with  claim 5 , comprising:
 displaying a video recording of the person ambulating, or a rendering of the video recording of the person ambulating as a three-dimensional stick figure with a plurality of segments representative of a skeletal model of the person, with data from the IDA and AA overlaid on one another. 
 
     
     
       7. The method in accordance with  claim 1 , further comprising:
 arranging a plurality of video cameras at a predetermined spatial volume; and 
 calibrating the plurality of video cameras by recording an initial predetermined pose of the person. 
 
     
     
       8. The method in accordance with  claim 1 , further comprising:
 arranging the pair of foot sensors on the person's ankles, feet, shoes or lower limb prostheses; and 
 calibrating the pair of foot sensors by zeroing the pair of foot sensors and having the person stand on a scale, one foot at a time sequentially. 
 
     
     
       9. The method in accordance with  claim 1 , further comprising:
 creating a patient history file comprising patient information including patient height, patient weight, patient mass distribution and patient body fat; and 
 saving the patient information together with the data file of the kinetic data and the kinematic data. 
 
     
     
       10. The method in accordance with  claim 1 , further comprising:
 analyzing the kinetic data and the kinematic data together; and 
 reporting analysis of the kinetic data and the kinematic data. 
 
     
     
       11. The method in accordance with  claim 1 , further comprising:
 displaying a video recording of the person ambulating, or a rendering of the video recording of the person ambulating as a three-dimensional stick figure with a plurality of segments representative of a skeletal model of the person, with the kinetic data measured by either of the pair of force sensors overlaid one another. 
 
     
     
       12. A system for analyzing movement of a person, the system comprising a pair of 3D force sensors configured to be affixed to a person's ankles, feet, shoes or lower-limb prosthesis and configured to measure 3D kinetic data as the person ambulates, each of the pair of 3D force sensors comprising an at least three-axis sensor capable of sensing at least pressure force or vertical force, anterior/posterior shear force, and medio/lateral shear force, a digital memory device capable of storing the 3D kinetic data, a mobile processor capable of producing a left or right side identified vector quantity, a transceiver capable of wirelessly transmitting the 3D kinetic data at 60 Hz or greater a computer with one or more processors and a transceiver; at least one video camera configured to record markerless 3D kinematic data as the person ambulates in an environment without force-sensing plates; and the one or more processors configured to:
 temporally synchronize the kinetic data from the pair of force sensors and the kinematic data from the at least one video camera together from a visual event created in the 3D kinematic data captured by the at least one video camera and a force event created in the 3D kinetic data sensed by at least one of the pair of force sensors, or from a time signal sent from the computer to the pair of force sensors and a time-stamped vector quantity transmitted from the pair of 3D force sensors to the computer. 
 
     
     
       13. The system in accordance with  claim 12 , wherein the one or more processors is further configured to:
 orient a foot segment coordinate system of either of the pair of force sensors with a foot segment coordinate system of the lab space of the video camera by: 1) aligning a foot space vertical force component vector reported by one of the pair of sensors with a vertical axis created by the video camera, and assuming the force vector and vertical axis are parallel during flat foot while ignoring force generation during initial contact and heel off; or 2) rotating a force vector reported by one of the pair of sensors using Euler Conversion matrices to the lab space coordinate system of the video camera. 
 
     
     
       14. The system in accordance with  claim 12 , wherein the one or more processors is further configured to:
 adjust segment mass properties based on both visual blob segment distribution and choice of prosthesis by realigning mass distribution between a standard mass distribution of a non-amputee and mass distribution of the amputee with the prosthesis. 
 
     
     
       15. The system in accordance with  claim 12 , wherein the one or more processors is further configured to:
 render the video recording of the person ambulating into a three-dimensional stick figure with a plurality of segments representative of a skeletal model of the person; 
 perform Inverse Dynamics on a computer model based on the kinematic, the kinetic and segment data to calculate 3D joint forces and moments; 
 perform Intersegmental Dynamics Analysis (IDA) on a computer model based on the kinematic, the kinetic and segment data by applying joint moments to determine subsequent acceleration of the computer model; and 
 perform Acceleration Analysis (AA) to compute a contribution of net joint moments to forward propulsion of the person. 
 
     
     
       16. The system in accordance with  claim 12 , wherein the one or more processors is further configured to:
 display a video recording of the person ambulating, or a rendering of the video recording of the person ambulating as a three-dimensional stick figure with a plurality of segments representative of a skeletal model of the person, with the kinetic data measured by either of the pair of force sensors overlaid on one another. 
 
     
     
       17. A mobile gait lab system, the system comprising:
 a) a pair of force sensors configured to be removably affixed to a person's ankles, feet, shoes or lower-limb prosthesis and configured to measure kinetic data as the person ambulates, each of the pair of force sensors comprising: 
 an at least 3-axis ground reaction sensor configured to sense at least: 1) pressure force or vertical force, 2) anterior/posterior shear force, 3) medio/lateral shear force, and 4) torque or moment exerted between the person's ankles, feet, shoes or lower-limb prosthesis and a support surface about a first vertical axis; 
 b) a plurality of video cameras configured to record markerless kinematic data as the person ambulates in an environment without force-sensing plates, the plurality of video cameras being removably disposed about a predetermined spatial volume; 
 c) a computer with one or more processors configured to: 
 temporally synchronize the kinetic data and the kinematic data together from a visual event created in the kinematic data captured by the plurality of video cameras and a force event created in the kinetic data sensed by at least one of the pair of force sensors, or from a time signal sent from a computer to the pair of force sensors and a time-stamped vector quantity produced by the mobile processor and transmitted from the pair of force sensors to the computer. 
 
     
     
       18. The system in accordance with  claim 17 , wherein each of the pair of force sensors further comprises:
 a) a housing; 
 b) a battery port with an opening; 
 c) a rechargeable battery insertable through the opening and into the battery port; 
 d) an attachment coupled to the housing and configured to attach the housing to the person's ankles, feet, shoes or lower-limb prosthesis; 
 e) a digital memory device disposed in the housing; 
 f) one or more mobile processors disposed in the housing and coupled to one of the pair of force sensors, and configured to receive force signals, convert analog s to digital signals, filter the signals, amplify the signals, condition the signals, compensate the signals and/or calibrate the signals; and 
 g) a wireless transceiver disposed in the housing and coupled to the one or more mobile processors. 
 
     
     
       19. The system in accordance with  claim 18 , wherein the one or more mobile processors are configured to produce a time-stamped, left- or right-side identified, 7-axis vector quantity; and wherein the one or more mobile processors and the wireless transceiver are configured to transmit the vector quantity at 60 Hz or greater.